The present invention relates to a system for determining spatial coordinates of points, and methods related to the calibration of a probe and its contact unit, and to the determination of the position of points in a network.
Norwegian Patent No. 174 025 describes a system for determining spatial coordinates of points on a face or an object, where the measuring probe is made in the form of a light pen having light sources at known coordinates relative to a probe-fixed coordinate system, and where the spatial coordinates are determined by registering the image of the light sources on a sensor in a single stationary camera. The position of the light pen is thus determined in a coordinate system given by the position of the camera. The system results in limited accuracy, given by the dimensions of the light pen and the visual field of the camera.
Norwegian Patents Nos. 164 946 and 165 046 describe systems and methods based on two or more stationary or movable cameras. Great accuracy is attained by using these in that the measuring point is observed from two or more camera positions.
The object of the present invention is to redress the limitations associated with the known solutions. The system according to the present invention is thus characterised by the features which are set forth in the patent claims below. The methods mentioned above are also characterised by the features set forth in the patent claims below. These and additional distinctive features of the invention will also be set forth in the following description with reference to the appended drawings.
New, miniaturised cameras make possible a hand-held probe containing a camera, and where its position and orientation are determined on the basis of registering an image of a fixedly mounted network of reference points. The difference from the previous system as described in Norwegian Patent No. 174 025 is thus that a network of reference points is stationary relative to the object which is to be measured, whilst the probe, which according to the present invention contains one or more cameras, is moved across the object which is to be measured. Considerably higher accuracy is attained with this solution than with the previously patented system based on one camera and light pen. This is due to the fact that images of several points can be made at each registration, and their geometrical distribution can be adapted such that they are distributed across the entire visual field of the camera and at different distances from the camera-based probe.
The accuracy attainable with this system solution is comparable to what was previously attainable with a minimum of two cameras which view the object which is to be measured from two different directions of observation. This invention thus provides a system which is far simpler, is low in weight and complexity, and low in production costs.
The probe can be made wireless in that the image is transmitted from the camera to a central unit by radio signals or infrared communication.